Method of making a white pigment.



H. W. KBSSLER.

METHOD or MAKING'A WHITE PIGMENT.

APPLICATION FILED D30. 22, 1909.

L1 ail-1% 1 I Patented Mar. 9, 1915.

HENRY W. KJESSLIER, F CLEVELAND, OHIO, ASSIGNOR TO THE KESSLER COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

METHOD OF MAKING- A WHITE PIGMENT.

Specification of Letters Eatent.

Patented Mar, 9, 19115,

Application filed December 22, 1909. Serial No. 534,407.

To all whom it may concern.

Be it known that ll, HENRY W. KEssLER, a citizen of the United States, and a resident of Cleveland, county of Cuyahoga, and State of Ohio, have invented a new and useful Improvement in Methods of Making a White Pigment, of which the following is a specification, the principle of the invention being herein explained and the best mode in which it have contemplated applying that principle, so as to distinguish it from other inventions.

Despite numerous improvements that have been made in the manufacture of white pigment of lead since the old Dutch pr0cess was the prevailing commercial process, the best of the present day methods involve a considerable waste of time and of material, not to speak of the energy consumed in handling large quantities of liquid, since all such processes, so far as I am aware, are wet in character.

The object of the present improved method, is to simplify the manufacture of the compound in question, and to eliminate all necessity for the use of water or other liquid during the manufacturing stages other than the relatively small quantity re quired for hydration so that the pigment is obtained in the dry form in which it is desired for its further handling and use.

To the accomplishment of these and related objects, said invention consists of the steps hereinafter fully described and particularly pointed out in the claims.

The annexed drawing and the following description set forth in detail one approved method of carrying out the invention, such disclosed mode, however, constituting but one of the various ways in which the principle of the invention may be used.

Tn said annexed drawing the single figure there appearing, is a more or less diagrammatic representation of apparatus adapted for the carrying on of my improved process of manufacture.

The general principle underlying such process or method of manufacture, is the direct combination or union of lead oxid, while in a finely comminuted condition, with carbonic anhydrid, or carbon dioxid gas, sufficient moisture being present to produce the hydrated carbonate desired, that is cominercial white lead. Various forms of apparatus may be utilized in carrying out such process. the typical one illustrated serving merely as a basis for a more detailed description of the steps involved, for it is not thought that such apparatus requires description apart from the general description of the steps in question;

Disintegrated powdered lead obtained by any suitable process or apparatus, is thrown into a feeding hopper 1 provided with a screw feed 2, by which such lead is continuously fed into the air jet 3 of a blow pipe 4- that discharges into a large chamber to be presently more particularly described. A blower 6 is provided for forcing the air through such air jet, while the latter is surrounded by a pipe 7 connected with a gas main so that gas may be supplied to said pipe to be mixed with the blast of mingledair and powdered lead discharged from the air jet 3. Upon ignition of such mixture of lead, air and gas, the flame of the gas encircles the air pipe surrounding the escaping air blast which carries the powdered lead and burns the latter into the oxid. The chamber 8 into which such blast discharges should be of ample proportions and is preferably of the general cylindrical form shown, being disposed withits axis vertical and having its respective ends provided with openings. Of these openings, the lower one 9 is utilized in removing from the interior of the chamber any solid material therein; the upper one 10 on the contrary serves to conduct away the mixture of gases and vapors produced by the combustion of the lead and the further reaction taking place inor beyond said chamber. An additional opening 11 is provided into said chamber by means of which carbonic anhydrid, or carbon dioxid ((30,), may be supplied in any desired quantity to such chamber, so as to maintain therein a body of this gas to the substantial exclusionof all others, except those discharged along with the powdered lead. Along with such carbon dioxid,

or else with the air supplied through blower 6, a certain quota of water, preferably in the form of steam, may also be introduced into the reaction chamber 8. Some water will of course be produced by the combustion of the gases discharged into the chamber from the burner, but this may not ordinarily be sufiicient for effecting the required hydration. This water, or steam, it is further assumed, enters directly into the reaction whereby the white lead is formed, as is indicated in the reaction given below.

A conduit 12 connected with the upper end of the chamber 8 leads thence into a series of settling chambers 13, of which two form where the last trace of any solid material is removed. This dust collector is provided with a chamber 16 at the top with which the pipe from the blower is connected, the products of combustion passing downward through cotton tubes 17 which retain all such particles, but permit'the gaseousproducts to escape. The particles constituting aforesaid solid materialare from time to time shaken from these tubes into a receptacle 18 at the bottom of the dust collector, from whichthey are removed as desired.

By means of the close regulation in the supply of air and gaseous hydrocarbon fuel rendered possible by the construction of the blow pipe 4, the substantially complete conversion of the powdered metallic lead into lead oxid (PbO) is effected. At the temperature at which combustion takes place, this oxid is in a very fine state of subdivision or comminution, and it thus persists for an appreciable time; accordingly, said oxid is drawn upwardly along with the ascending current of gases in chamber 8, and in so doing, is cooled to a degree such that it is acted on by the carbonic acid gas and moisture already introduced into the apparatus. Owing to its being thus so finely divided, said oxid is still susceptible to the action of the gases in question, taking on both the carbon dioxid and water, and forming hydrated lead carbonate. The chamber, it will be understood, may be externally heated, if necessary, in order to assist the ignited blast from the blow-pipe in maintaining a proper temperature therein. The temperature, of course, within said chamber, will be considerably lower than that at whichthe,

actual combustion of the lead takes place. The degree of heat at which the latter will burn, is, of course, well known, and I find natural gas a highly effective agent in both securing a thorough combustion of the pulverized metal, and the discharge of the resulting oxid into the chamber beyond the burner. As has been indicated, the carbonic anhydrid thus supplied, supplemented by that produced by the combustion of the hydrocarbon fuel injected along with the lead and air through blow pipe 4, constitutes substantially the entire gaseous body in said chamber 8 and the apparatus connected therewith, save for the small percentage of watery vapor previously referred to. In said chamber, .or at such point therebeyond, where the prevailing temperature of the intermingled gases and oXid are lowered to the proper point, it is found that in the presence of the water vapor, such anhydrid unites directly with the vaporized lead oxid by the simple reaction The manner in which the carbonate resulting from this reaction is separated out from the waste gases, should fully appear in the preceding description of the general operation of the apparatus illustrated. It

will accordingly be seen that by means of my improved method of manufacture, I am enabled to proceed by a single operation from the raw material to the finished product, no intermediate handling or attention being required. Both of these are points of considerable. consequence, since thereby the amount of labor required is materially reduced. At the same time the carbonate is obtained in pure, dry form and requires no further preparation before being put to use.

The theoretical amount of carbon dioxid and water that requires to be supplied to the chamber 8, for a given quantity of lead consumed at the burner 3, may, of course, be readily deduced by the reaction formula given above; as a matter of fact, however, I have found it desirable to maintain the carbon dioxid gas. and for that matter, the steam, considerably in excess of the theoretically correct proportion, since otherwise the product will remain constituted too largely. of the non-carbonated oxid.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the process herein disclosed, provided the step or steps stated by any one of the following claims or the equivalent of such stated step or steps be employed.

I therefore particularly point out and distinctlv claim as my invention 1. The method of making a white pigment, which consists in discharging an ig- Mamet mid, and then separating the carbonate from the gases insaid chamber.

3. The method of making a white pigment, which consists in burning powdered metallic lead and reacting upon the freshly formed lead oxid, with carbon dioxid and steam.

4. The method of making a white pigment, which consists in discharging an ignited combustible mixture of powdered metallic lead, air, and hydrocarbon fuel into a body of carbon dioxid, and admixed steam,

and then separating the carbonate from the gases wherewith it is mingled.

5. The method of making a'white pigment, which consists in discharging an ignited combustible mixture of powdered metallic lead, air, and gaseous hydrocarbon fuel into a chamber containing carbon dioxid, and admixed steam and'then separating the carbonate from the, gases 'in said chamber.

Signed by me this 20th day of December, 1909.

HENRY W. KESSLER.

Attested by ANNA L. GILL, JNo. F. OBERLIN. 

